Looonnnggg winded?! Lets have a discussion!

I have owned a few IDI's but I just bought my first one with a turbo (see sig) It is a really nice truck that's for sure.

This replaced my first gen Cummins so I instantly picked out things I don't like about the engine and other things that I do in comparison. One thing that I don't like (even compared to 7.3 PSD's) is how long winded it is. It feels like I have to stand on the throttle forever and by the time the boost hits 7-10psi it doesn't build any more power at all. I have the 088 turbo so maybe a waste gated unit would help out? Is there any way to build boost without having to rev the engine to the moon or is that just the nature of this beast? I don't like to rev diesels and I never really have. The way I like to drive I don't ever see more than 2psi...

No boost until high rpms = waste of fuel and doesn't take advantage of the engines low end grunt imo What do you think? Any ideas?

Rot Box said:

No boost until high rpms = waste of fuel

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But saves the reciprocating assembly from cylinder pressure spikes and possible meltdown.

I agree with you tho. My Banks non-gated charger doesn't really make power until about 2200, and from there on out will put you back in the seat, even it 5th. It pulls ******* the topend, but is super doggy on the bottom end.

A gated charger will do better, but IMO, none of the available setups will be up to your liking, nor mine. Having driven others, it's hard to step back in the power/power delivery, but that's the nature of the beast with these trucks.

I almost learned the hard way if you are pulling hard and using boost, you need the rpms up. I was pulling up the side of Afton mountain with a GM turbo diesel in a old state truck(I think it's a 8.3?) with a backhoe on a trailer. I had it in a higher gear and had it floored, and my wife was with me and said the black smoke was pouring out of the stack. The farther I went the hotter temp gauge got till I wised up and used a lower gear(I hit about 230 on the gauge). The revs went up but the temperature of the engine went down.

I mentioned this to some people more knowledgeable than me about diesels and towing, and they said keeping the rpms up allows more airflow through the engine especially with the turbo blowing through it, which helps keep it cooler when you are really using the engine.

I find that most diesels don't like to be lugged at all.

I'll never understand why some people (not you Franklin), turn their pumps up in order to make their motors smoke. ***

Black smoke is a sign of wasted fuel and (sometimes) a inefficiently set up motor.

Too each his own, I guess.

Thanks for the reply's so far

emmer said:

I find that most diesels don't like to be lugged at all.

I'll never understand why some people (not you Franklin), turn their pumps up in order to make their motors smoke. ***

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I am a firm believer that smoke = wasted fuel and wasted power.

I don't like to lug engines I am just saying that I don't like to have the IDI wrapped to the gills before they build boost.

The IDI's build torque very low in the RPM's and I would like the turbo to complement that power curve. I'm not sure how much my pump has been turned up (if any) but at low RPM's it smokes a little untill the turbo builds pressure and at that point it is really high in the RPM's.

Rot Box said:

Thanks for the reply's so far

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Lots of reall smart guys on here (not me) but still, tons of free and very usefull info.

First off, the 088 turbocharger isn't ideal for the 6.9. I've concluded that it is better suited to the larger displacement 7.3L and even then, its designed to wind out by 10 PSI. Thats why I wanted to upgrade mine. Bigger compressor housing and header wrap on the turbo pipes both helped and make it much more responsive. You have to remember that ATS designed that setup to be reliable on a STOCK IDI, not a studded engine with dropped compression or intercooler (or other mods). 10 PSI is a good safe limit at which they could be confident that their turbos would not blow up the engines they installed them on.

What kind of winding up are we talking about here?

2000 RPM is good for cruising with a load, but if you have to get moving, you need to wind it up. Turbo boost is one reason, controlling EGTs is another, but there is also the issue of oil pressure. Too much boost at lower RPM could over load the bearings where at higher RPM, oil pressure is enough to keep lubrication going.

What sort of smoke are you seeing at those boost pressures? A slight haze right at peak is ok, but if you are rolling coal at 2500+ and 10 PSI, then something is off. maybe timing.

torque peaks at 1500ish turbo should add to that, not move it up in the rpm. my truck was pretty slow to build boost, wrapping pipes helped a bunch, the intercooler also helped. at 2k unloaded i can make 6-7lbs pretty easily. before I did the intercooler I was convinced I needed a wastegated kit, now Im very happy with how it runs.

I agree with david85, oh and I sold him the turbo parts. .. If you still have a muffler, dump it, go 4 inch right after the downpipe, turn up the fuel a little, wrap the up pipes. Then mod the turbo for more low speed boost. The wastegated turbo will build lower but is a little restrictive on the top end.

Also a change to a torque cam helps also.

Oh, yeah about that exhaust pipe??

I have a 3" with a 4" muffler. Not ideal......

One thing I forgot to mention about the 088 is that while the boost may be dissapointing, it has excellent EGT control and so far I haven't found anyone that can pull like mine does and still have EGTs as low as they are on mine. I have to go nuts to even touch 1000, but typically hit a wall at 900.

well,on my 94, i got the ats upgrade part,turned up the pump,turned up the boost to max 13. i can stand on the throttle from a dead stop--and the tires start to roll over--serious-----maybe i have a oddball--and it will keep rolling them, till im moving past 30------------NOW RUSS--how much would a tq cam help me after saying that??

also timing makes a world of difference in smoke and turbo spool time. back the timing off a bit and the smoke will be less and the turbo will spool quicker. Ive run my timing anywhere from 0-10degrees and never been able to measure more than a couple tenths in mileage.

typ4 said:

The wastegated turbo will build lower but is a little restrictive on the top end.

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What about a modded or enlarged wastegate? Or an external gate? 1000+hp sledpullers/racers have been implementing external gates with tremendously good results. Tighter housings for good initial spoolup, then a modified gate, or external, for good flow on the topend. It's kind of the best of both worlds. Granted, we are building alot less power, but the principal operation stays the same.

My opinion is that we need to look into other sources for a turbocharger. I've been talking with Turbonetics about a charger that they have had available for several years now, and they feel it would be a very good addition to an IDI. It's been used widely by import tuners, and is marketed as a 450hp turbocharger. It move enough air to easily put one of these motors at that figure, would just need to find the appropriate housing sizes to make in efficient.

Push the envelope and think outside the box. Cummins guys started out with upgrading to other out of the box Holset chargers, then started getting into the Borg Warner/Schwitzer heavy duty large displacement turbos, and now have several shops modifying S300/400/500 based turbos to work with their application. Who would've have thought you could run the stock turbo off a Detroit Series 60 12.7L semi engine in your daily driven 5.9L Cummins? It's a balance of housing sizes, modified trim on the wheels and so on. It's not the same thing that came off a 12.7L, but it's the same frame and basic structure, that's been modified to work.

Black dawg said:

also timing makes a world of difference in smoke and turbo spool time. back the timing off a bit and the smoke will be less and the turbo will spool quicker.

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Lower timing always winds up in higher EGT's, since more of the burn happens after TDC and into exhaust, and tranlates into better spoolup. SLIGHTLY lowered power and mpg are noted with lower timing, as it's not as efficient at burning all the fuel for the power stroke.

a big external gate would be the cats ass, full boost by 1500 and decent drive pressure all the way to dyoung14 engine speed and beyond. Ive wanted to upgrade my turbo for awhile, but on a compressor map they are not that bad.